DE3414067A1 - OVERLOAD PROTECTION - Google Patents

Description

GdA, Gesellschaft für Digitale Automation mbH, Lützelsteiner Straße 1, 8000 Munich 45

Overload protection

The invention relates to an overload protection device, in particular for an industrial robot having a robot arm and a robot tool, preferably arrangeable between the robot arm and the robot tool, with a robot flange and a tool flange, wherein the tool flange is relative to the robot flange is movable.

Handling machines, in particular industrial robots, are often relatively bulky, relatively large or relatively moves heavy objects and at a considerable speed. Here is always the

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Munich Office (patent attorneys only):

Postfach / P. O. Box 22 0137, D-8000 Munich Schlotthauerstraße 3, D-8000 Munich 90 Telephone: (089) '223311

Telescope. / Telecop .: (089) 2215 69 CCITT 2

Telegr. / Cables: Forbopat Munich

Telex: 524 2S2forbod

Accounts / Accounts:

Bank for Community Economy, Munich

(BLZ 70010111) 17 907 70200

Bremer Bank, Bremen

(Sort code 290 80010) 100144

Deutsche Bank. Bremen

(BLZ 29070050) IU 2002

PSchA Hamburg

(BLZ 20010020;] 26083-202 EPO COPY

Bremen / Bremen Office:

P.O. Box / P. O. Box 10 7127

Hollerallee 32, D-2800 Bremen

Telephone: (0421) '34 90 71

Telescope. / Telecop .: (04 21) * 34 90 71 CCITT

Telegr. / Cables: diagram Bremen

Telex: 244 95S bopat d

There is a risk that especially with projecting workpieces due to movements that significantly exceed the The basic dimensions of the industrial robot, contact with or collision with other workpieces, Machines or other objects located in the path of movement occur. One is therefore to it passed, between the tool and the robot arm an overload protection of the aforementioned Type to be built in, which thus represents a "predetermined breaking point", as it were.

In the case of an industrial robot, the maximum weight of a load that can still be moved with the industrial robot increases given drive power with increasing lever arm, i.e. with increasing boom width of the robot arm. Also diminishes that Weight of the robot arm itself is the "payload" of the industrial robot. For an overload protection of the talked about standing type result from these aspects framework requirements for the lowest possible axial Extension or construction depth and as small as possible Weight.

In the case of an overload protection device known from practice An electrical proximity switch is inserted into the robot flange, which is at a certain distance from the tool flange is arranged. When changing the distance between the tool flange and the robot

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flange responds to the electrical proximity switch and triggers a safety shutdown. This known embodiment of an overload protection device is initially already unsatisfactory with regard to the requirements explained further above with regard to the smallest possible structural depth and the lowest possible weight. The electrical proximity switch has a not inconsiderable length extension and also contributes significantly to the overall weight of the overload protection device at. In addition, with the known overload protection device, the tool flange has freedom of movement very limited, since it is constructed around the relatively elongated electrical proximity switch. Without such a comprehensive training, the overall depth of this known overload protection would be considerable again enlarge. The formation of the tool flange, which includes the proximity switch, results in certain For example, stresses on the industrial robot associated with a tilting movement of the tool flange can very easily result in damage the overload protection. However, this results in a limited applicability of this overload protection.

The proximity switches as electrical switching elements can also fail due to electrical defects, in which case the ' It is usually necessary to replace a proximity switch. If the proximity switch itself is not defective, it can however, especially in the case of an industrial robot that is constantly in motion, damage to the electrical ones Supply lines occur.

In this prior art, the invention is therefore based on the object of an overload protection device indicate the minimum possible depth and

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BOEHMEKT * &; öp ^

As light weight as possible, it can be used more extensively and at the same time is more reliable.

This object is initially and essentially achieved in that the robot flange and the tool flange in a sealing area acted upon by a pressure medium cooperate sealingly and that a safety shutdown by a pressure drop in the pressure medium can be triggered.

The configuration according to the invention thus results in overload protection, in which an electrical proximity switch is completely dispensed with. According to the invention checking the distance between the tool flange and the robot flange caused by a simple sealing area between these two flanges, which is only a minor structural Requires effort, in particular only a very small overall depth, while at the same time that for this sealing area necessary constructive measures reduce the weight of the overload protection noticeably. Essentially they only exist in recesses, in which on the one hand the print medium is guided and on the other hand Sealing lips are held, moreover, is a special Another advantage to be noted is that the overload protection device according to the invention is also much easier to maintain. In the case of the known overload protection device described above can it e.g. B. come to a failure 'of the electrical proximity switch. Because this is fixed in the robot flange is, the entire overload protection must first be dismantled in order to replace this proximity switch to be able to.

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- BOEHMERT-'ÄTSpEFj ^ IERT - "-:.

'The above in the formulation of the inventive The term "print medium" used in teaching is in the frame to understand the invention in a very broad sense.

It does not necessarily have to be something that is only used as such Pressure medium such as oil, gas, "water, etc., but the success of the invention is also about a (flexible) Line reached in which the print medium is guided.

If, as provided in a preferred embodiment / compressed air is used as the pressure medium, there is a particular advantage in the inventive Overload protection by a blow-out effect that occurs when the overload protection is triggered. the When the overload protection is triggered, air under pressure escapes essentially radially and blows away any dust particles or the like near the sealing area. So can be in the - then opened - Do not deposit any dust or the like in the sealing area, which would reduce the sealing effect.

Another shortcoming in the known overload protection is a lack of adaptability of the release load. The tool flange is over on the robot flange a compression spring is supported, on the one hand on a bolt support flange of a mounting bolt and on the other hand on a support flange of the robot flange and a relative movement between the tool flange and the robot flange only from a certain one Load allows. If the permissible load changes, be it that by the industrial robot or the Handling machine objects of different weights or dimensions are to be moved, so an adjustment can be made overload protection can only be achieved by replacing the compression spring. However, this is the case with the known overload protection associated with a relatively large effort, which causes a considerable downtime.

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BOEHMERT S; ^^>;

According to a further teaching of the invention, which is also independent Is of importance, this inadequacy is overcome-r-that-the retaining bolt in the tool flange is supported axially displaceable and adjustable in accordance with a pre-tensioning force to be selected. In the . This bracket can be carried out individually in various ways, whereby the person skilled in the art is familiar, for example, with the the end of the retaining bolt associated with the tool flange to be provided with a thread and the axial position of the. Bracket bolt over two braced against each other Adjust nuts. A preferred embodiment of this axially displaceable holder is shown below in individually explained.

The teachings according to the invention, the tool flange and the Designing the robot flange to cooperate in a sealing manner in a sealing area also allows tilting movements of the tool flange relative to the robot flange. As an adaptation to these possibilities of movement, in Another embodiment of the invention provides that the bolt support flange in its support area is designed like a spherical cap and interacts with a correspondingly designed support ring, on which the compression spring rests. A deflection of the retaining bolt from its axial position then results a ball-joint-like displacement of the bearing ring on the bearing area. The ones that coincide in normal position The axes of the retaining bolt and the compression spring form an angle with one another in this case a.

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BOEHMEtrT * £ feO £ WERI - '.'. "I - ■

The axially displaceable and adjustable bracket of the , - <· The retaining bolt is preferably realized in that the retaining bolt on the tool side of the tool flange has an adjusting head equipped with a lifting surface has, and that a radially movable, with a complementary to the 'lifting surface formed adjusting surface provided and cooperating with the adjusting head adjusting element is provided for the axial Displacement of the mounting bolt. The radial arrangement of the adjustment element enables adjustment of the Retaining bolt with the least possible effect on the overall depth of the overload protection device. Also are the controls very easily accessible from the outside without even having to dismantle the tool to remove the mounting bolt set or readjust. If the overload protection device has been implemented, two setting elements are provided. ; * seen the one with two adjustment surfaces of the mounting bolt

ι cooperate, the adjustment surfaces in a transverse

main of the mounting bolt are formed, which thus has an overall T-shape.

To a .reliable response of the overload protection also with torsional loads, d. H. Stresses affecting the tool flange relative to the robot flange (only) looking to twist, to ensure, is provided according to another feature of the invention that the robot;

flange has at least one deflector cam on the tool flange side and that the tool flange has a corresponding recess on the robot flange side. It has proven to be particularly advantageous to design the deflector cam as a deflector cylinder and to arrange it in such a way that a longitudinal axis of the deflector cylinder is aligned with a center point of the robot flange. Of particular importance is also the measure to provide the Abweiserzylinder in diameter with a slight excess in comparison to the recess, giving a ^ ^e finierte, safe and against a wear attack. results in largely insensitive support position. ),

BOEHMERT & .S0EBMERT · .- *: -.

Another measure that. also to a lower wear attack leads, but also has advantages in terms of an easy response of the overload protection. According to this measure, it is provided that the deflector cylinder is slightly "sunk" into, for example, the robot flange is arranged. In other words, the effective Deflector surface of the deflector cylinder has a smaller circumferential extent on as TC corresponds to r, where r is the radius of a cross-sectional circle of the deflector cylinder. With this, a wedge effect of the deflector cylinder is achieved, as it were, which will be explained in more detail below is described in more detail.

Even if the advantages described above already result with a deflector cam, it is in a practical configuration but it is provided that several deflector cams or deflector cylinders are formed, and that the deflector cams or deflector cylinder are arranged asymmetrically distributed. In the case of a symmetrical distribution, Rotation of the tool flange relative to the robot flange the robot flange "snaps" back into its starting position, which, depending on the tool, may already be is not wanted.

The deflector cams can in principle be provided both in the robot flange and in the tool flange be, and the corresponding recesses in the other flange. However, it is preferred that that the deflector cylinders are arranged in the robot flange and, accordingly, the associated recesses are incorporated into the tool flange. This is advisable from the fact that in any case the Tool flange is movable relative to the 'robot flange.

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The described configuration of the instruction cams is also advantageous from a manufacturing point of view. As well as There is a recess in both the tool flange and the robot flange incorporate, in a deflector cylinder on the one hand is held, on the other hand, in the normal position of the flanges fits together. This cylindrical recess can be worked out, for example by drilling, with joint clamping of the flanges, with which without further ado it is ensured that the necessary recesses are angularly in the tool flange and the robot flange exactly matching places.

With regard to the teaching according to the invention described at the beginning, the robot flange and the tool flange in FIG to form a sealing area sealingly cooperating, a special embodiment is that the The sealing area is sealed by sealing lips embedded in the tool flange, albeit here In principle, a reversal is possible, namely that the sealing lips are let into the robot flange. The sealing lips are held in the tool flange in grooves that have a cross-section to the surface of the tool flange are designed to be tapered. For example, this can be done by an undercut on the one hand straight on the other Flank of the groove be realized. The sealing lips are thus held in place effectively and in a simple manner.

On the robot side, the sealing area consists of a groove in which the pressure medium is guided, this groove being in the Sealing state is then sealed by two sealing lips that run on both sides. The print medium is taken from a pressure medium line in the industrial robot, which is normally with a relatively high Pressure is applied. However, since the level of pressure of the pressure medium in the sealing area for the function

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BOEHME ^ T & I ^ OEHME-RT, f ->: _ _: _

the overload protection has practically no meaning According to a further preferred embodiment it is provided that the feed line to the sealing area is a throttle device and that the safety switch 'in the flow timing direction of the pressure medium behind the throttle device is arranged and is in active connection with the supply line. This is the safety switch only applied with a low pressure, so does not require any special structural effort.

In the following the invention is based on only one a drawing illustrating an embodiment is explained in more detail, on which shows:

1 shows a cross section through an overload protection device according to the invention;

FIG. 2 shows a plan view of the object according to FIG. 1;

Fig. 3 is a schematic diagram of a print medium circuit diagram and

FIG. 4 shows a sectional illustration of the object according to FIG. 1, cut along the line IV-IV.

An overload protection device is shown and described, which is intended in particular for use in an industrial robot. The overload protection exists in essentially from a robot flange 1 and a tool flange 2, which cooperate in a sealing manner in a sealing area 3 acted upon by a pressure medium. A safety shutdown can be triggered by a drop in pressure in the print medium.

BOEHMUiT ^ ttOERNI

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Such an overload protection is used in an industrial robot placed between a robot arm and a tool to prevent the industrial robot from being switched off if it is not permitted to trigger high weights or loads. In the case of the JFi-g. 1 is a connection flange 22 of the robot arm can be seen, while the tool is not shown.

Of the. WerOczeugf lansch 2 on which the tool is in the operating state is flanged is movable relative to the robot flange 1, namely via the bracing of the tool flange 2 against the robot flange 1 by means of a compression spring 7. H. the preload in the compression spring 7 exceeding load-lifts the Werk.z.eugflansch 2 from the robot flange 1 and "There is a pressure drop in the sealing area 3, to which a safety switch 21 (see FIG. 3) responds.

As can be seen in detail in Fig. 1, the compression spring 7 is supported on the one hand on a bolt support flange 5 of a mounting bolt 4, which is axially movably guided in the tool flange 2, and on the other hand on a support flange 23 of the robot flange mounting bolt 4 can be changed 11, which is arranged radially to the support pin 4 by means of a _T J- ^ adjustment member. The adjusting element 11 is provided with an external thread and the bore in the tool flange 2, which receives the adjusting element, is provided with a corresponding internal thread. The input ~ 'position is thus by simple helical encryption'"Δ rotate adjustment member 11 can be carried out. In the embodiment shown in Fi.g.- 1! Embodiment is one of the inputs

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'Actuating element 11 separate lifting surface head 24 is provided. which is only radially displaceable, while "the adjusting element 11 also due to the described

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BOEHMERT & ^ gHMfRT; ί:.: .-> - 1:.:.

Thread guide is rotatable. In principle, the setting element 11 could also be embodied in one piece by about the head cooperating with the adjustment head 9 of the mounting bolt 4 is conical. The particular advantage of the radially arranged adjusting elements 11 is to be seen in that .that also a Adjustment or adjustment to changed conditions of the compression spring 7 made with the tool attached can be.

The adjustment head 9 of the mounting bolt 4 has lifting surfaces 8 which interact with the lifting surface head 24, are provided on the adjustment surfaces 10. It can be seen that both the lifting surfaces 8 as well as the Adjustment surfaces 10 run obliquely to the axis of the mounting bolt 4. As can be seen in particular from Fig. 2, the mounting head 9 has two spaced apart lifting surfaces 8, which in the total T-shaped adjustment head 9 are located to the side of the shaft of the mounting bolt 4. Corresponding These two lifting surfaces 8 each act with an adjusting element 11 or a lifting surface head 24 together.

As a closer examination of FIG. 1 shows with regard to the bolt support flange 5, the compression spring is located only indirectly on the bolt support flange 5. Direct it is supported on a bearing ring 6, which cooperates with the bolt bearing flange 5 in its Area this is designed in the manner of a spherical cap. The bolt support flange 5 and the Support ring 6 thus work together like a ball joint, causing the axes of the retaining bolt to diverge 4 and the compression spring 7 is possible.

BOEHMERT & BOtHNiERi: ::.; .-> -; ':.: -

To lift the tool flange 2 from the robot flange 1 are to be brought about even when the tool of the industrial robot is (only) subjected to torsional stress Deflector cylinders 12 secured in the robot flange 1 are provided, on which the tool flange 2 rests. By doing Tool flange 2 are provided with recesses 13 corresponding to the deflector cylinders 12.

As can be seen from FIG. 2, the exemplary embodiment as a whole five deflector cylinders 12 are provided, which are arranged distributed asymmetrically, but with their Longitudinal axes 14 are each aligned with the center point 15 of the robot flange 1. Basically, the inventive Success can of course also be achieved with fewer deflector cylinders. In principle it is already about three Abweiserzylindern 12 has the effect that the tool flange 2 rests centered on the robot flange 1. With a smaller number of deflector cylinders 12 a separate centering measure is otherwise necessary, for example by inserting the seat 30 of the tool flange 2 is formed rounded in the robot flange 1, where on the other hand, in the exemplary embodiment, as can be seen in FIG. 1, the tool flange 2 is not in contact with the robot flange 1 in the area of the seat 30.

As a further special feature, in FIG. 1 and in particular in FIG. 4, the deflector cylinder 12 is deeper in the robot flange 1 are embedded than it would correspond to a "symmetrical" bracket, even if this "asymmetry" in Figs. 1 u. is exaggerated for identification. An only slightly deeper recess is sufficient.

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BOEHMERT & BOEHMtRt [I.:. ' X:.:.

This asymmetrical mounting of the deflector cylinder 12 is of particular importance for proper lifting of the tool flange 2, especially in the case of torsional stress. This is intended to be the case in FIG. 4 Make the triangle of forces clear, which shows that the resulting force directly impacts the tool flange 2 is looking to take off. The drawing of the triangle of forces directly above the gap between the tool flange 2 and the robot flange 1 should not mean that the tool flange 2 rests on a deflector cylinder 12 only in this area. Much more is the tool flange 2 despite the measure described below "larger diameter" mostly directly on a wine bottle

12 on. Overall results from the described asymmetrical mounting, as it were, a wedge effect of the deflector cylinders 12.

The deflector cylinders 12 are in the robot flange 11 For example, held by a screw connection, but this is not shown.

With the described deeper mounting of the deflector cylinder 12 in the tool flange 1, the first effective deflector surface 16 of the deflector cylinder 12 with the corresponding recess 13 in the tool flange 2 in the normal position of the tool flange 2 no longer or are only in contact on one side. Furthermore, it is therefore provided that ~ the deflector cylinder 12 with a slightly larger diameter than the recesses

13 or the corresponding recesses in the robot flange 1 are selected.

It is also important that the deflector cylinders 12, as can be seen in FIG. 2, are arranged so as to be distributed asymmetrically are, which leads to the advantage already described above.

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BOEHMERT & BOEHMERi:

The sealing area 3 is formed in detail from sealing lips 17, which are held in_Nuten_18 and one Pressure medium groove 25, as can be seen in FIG. 1, when the tool flange 2 and the robot flange lie tightly against one another 1 is closed on both sides by sealing lips 17. The design of the grooves 18 is particularly advantageous, those in cross-section — to — the surface of the tool flange are designed to be tapered. As can also be seen in FIG. 1, the groove 18 is undercut on one side for this purpose educated.

A particular advantage of the overload protection device according to the invention is still that the robot flange 1 is exposed to only very low mechanical stresses, in particular due to the deflector cylinders 12 provided, which are used as separate parts in the robot flange 1 will. This makes it possible to design the robot flange 1 relatively freely in terms of material, which is, for example, the choice a light material, in particular a light metal such as aluminum, which allows again a considerable weight saving can be achieved.

Finally, FIG. 3 shows a circuit diagram for the pressure medium, the sealing area 3 is symbolized, namely in the illustrated state in the sealed state. It is essential that the print medium of a pressure medium line 26 is removed in the industrial robot and that between the pressure medium line 26 and the supply line 19, a pressure control valve 27, the pressure keeps constant on the outlet side, and a throttle device is switched, whereby in the lead 19 a relative low pressure is adjustable. This also has the advantage that when the safety shutdown is triggered does not use a disproportionate amount of print media

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the overload protection escapes. The safety switch

As can be seen in Fxg-, 3-, 21 is connected to the supply line

switched on, so also acted upon with relatively low pressure- .. ■

The throttle 20 is preferably designed so that in the steady state it only allows an amount of pressure medium to pass through which is only slightly greater than the amount that emerges in the stationary state in the sealing area. In this way, the least possible escape of pressure medium can be ensured in the switching state. At the same time, however, this measure also achieves a considerable "sensitivity" of the overload protection. The overload protection responds even if the pressure medium escapes in the sealing area at a slightly higher level than corresponds to a normal leakage loss.

Is of particular importance in the context of the invention nor the special design of the tool flange 2 and the robot flange 1 in the area of the fastening screws. As can be seen in particular from Fig. 1 of the drawing, fastening screws 28 are provided, with those of the robot flange 1 on the connection flange 22 can be fastened. There is also a tool of the industrial robot - not shown in the drawing can be screwed to the tool flange 2. The necessary for this, provided with a thread Bores 29 are provided coaxially to the threaded bores for the fastening screws 28. As far as a tool is not yet attached to the tool flange 2 of the overload protection is screwed, as shown for example in Fig. 1, the fastening screws 28 tightened or loosened through the bores 29.

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The ir. The above. Description, the Zeicr.-nunc and features of the invention disclosed in the claims both individually and in any combination for the embodiment of the invention in its different Appearance forms are important.

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ΒΟΕΗΜΞΚΤ & b'yLHM

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4th 3 sealing area • 4 mounting bolts ^ Stud spacer flange ^ Λ · ^ La ^ cjrrxijQ 7 compression spring β lifting surfaces • ·. ^ ^- . 9 adjustment head 1 "2 10 adjustment surface 11 adjustment element 14th 12 deflector cylinders 1J recess 14 longitudinal axis (of 12) 15 center point (of 1) £ 1 16 effective deflector area 1 ° 17 sealing lips ? 0 13 groove ?1 19 supply line 22nd 20 throttle device P ^ 21 Safety switch 22 connection flange 23 support flange 24 flat head 25 media groove PiZ ₁ pressure medium line

Pressure regulator _ ₇

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Seat

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Claims (1)

BOEHMERT & f 34H067 GX.M 1147 Expectations 1. Overload protection, especially for a robot arm and an industrial robot having a robot tool, preferably able to be arranged between the robot arm and the robot tool, with a robot flange and a tool flange, wherein the tool flange is movable relative to the robot flange, characterized in that that the robot flange (1) and the tool flange (2) can be acted upon by a pressure medium Sealing area (3) cooperate sealingly and that a safety shutdown by a Pressure drop in the print medium can be triggered. 2. Overload protection, in particular according to claim 1, wherein the tool flange on the robot flange over a compression spring is supported, on the one hand on a bolt support flange of a mounting bolt and on the other hand on a support flange of the robot flange supported, characterized in that the retaining bolt (4) in the tool flange (2) axially is held displaceably and adjustable in accordance with a pre-tensioning force to be selected. 3. Overload protection device according to claim 2, characterized in that that the bolt support flange (5) in his BOEHNtERT & Support area is formed like a spherical cap and cooperates with a correspondingly designed support ring (6) on which the compression spring (7) rests. 4. Overload protection according to claim 2 or 3, characterized ge -... indicates that the mounting bolt (4) on the tool side of the tool flange (2) has a lifting surface (8) equipped adjusting head (9), and that a radially movable, with a complementary to the Adjustment surface (10) provided with the lifting surface (8) and interacting with the adjustment head (9) Adjusting element (11) is provided for axial displacement the retaining bolt (4). 5. Overload protection according to one of claims 1 to 4, t characterized in that the robot flange (1) is . a 'at least one deflector cam (12) on the tool flange side and that the tool flange (2) is on the robot flange side has a corresponding recess (13). 6. Overload protection device according to claim 5, characterized in that that as a deflector cam (12) a deflector cylinder (12) is provided, and that the deflector cylinder (12) with its longitudinal axis (.14): on a center (15) of the Robot flange (1) is aligned. 7. overload protection according to claim 6, characterized / that an effective deflector surface (16) of the deflector cylinder (12) has a smaller circumferential extent than TC r, where r is the radius of a cross-sectional circle of the deflector cylinder (12). _ 8. Overload protection according to one of claims 6 or 7, * EPO COPY BOEHMERT & BOEHWETlJ '; ~ -': ":" ■ -: · "" · '"34H067 characterized in that the deflector cylinder (12) has a slightly larger diameter than the associated cylindrical recess (13) of the Tool flange (2). - ■ - " 9. Overload protection — according to one of claims 5 to 8, characterized in that several deflector cams (12) or deflector cylinders (12) are provided, and that the Deflector cams (12) or deflector cylinder (12) are arranged asymmetrically distributed. 10. Overload protection device according to one of claims 1 to 9, characterized in that the sealing of the sealing area (3) by means of sealing lips (17) embedded in the tool flange (2). 11. overload protection device according to claim 10, characterized characterized ^fc marked that the tool flange (2) has grooves (18) for holding the sealing lips (17) and that the grooves (18) in cross-section to Oberlfäche of the tool flange (2) tapering are trained. 12. Overload protection according to one of claims 1 to 11, whereby the industrial robot has a print media line with possibly has reltiv high pressure, characterized in that a feed line (19) to the sealing area (3) a Has throttle device (20) and that a safety switch (21) is arranged in the flow direction of the pressure medium behind the throttle device (20) and with the supply line (19) is in operative connection.